Surface condensor

ABSTRACT

A SURFACE CONDENSOR FOR STEAM GENERATE BY NUCLEAR POWER INCLUDES A PLUALITY OF COOLING TUBES ARRANGED IN A COMMON CASING HAVING INLET OPENINGS FOR STEAM AND AN OUTLET OPENING ABOVE A PLURALITY OF BASINS FOR COLLECTING CONDENSATE. EACH BASIN IS PROVIDED WITH A CLOSEABLE RETURN CONDUIT FOR PURE CONDENSATE CONTAINING A VALVE WHICH IS NORMALLY OPEN. THERE IS ALSO A LINE THROUGH WHICH POLLUTED LIQUID CAN BE DRAWN OFF FROM ANY BASIN PROVIDED WITH A NORMALLY CLOSED VALVE. AN ARRANGEMENT FOR MEASURING THE POLLUTION IN EACH BASIN OPENS THE VALVE FOR POLLUTED LIQUID IN RESPONSE TO A LEAKAGE OF COOLANT FROM THE TUBES AND AT THE SAME TIME SHUTS OFF THE FLOW TO THE LEAKING TUBE BUNDLE. THE CASING ALSO SUPPORTS A HOUSING ENCLOSING A PLURALITY OF TURBINES WHICH ARE FED BY THE STEAM AND WHICH DISCHARGE TO THE CONDENSOR.   D R A W I N G

United States Patent [191 Fejes SURFACE CONDENSOR [75] Inventor: Peter Fejes, Vasteras, Sweden [73] Assignee: Asea Atom AB, Vasteras,

, Sweden [22] Filed: Apr. 12, I971 [2]] Appl. No.: 133,095

[52] US. Cl. l65/10l, 165/111 [51] int. Cl F281 27/02 [58] Field of Search ..165/70,7l,110,l01, 113;

[56] References Cited UNITED STATES PATENTS 3,194,021 7/1965 Peake et al. 60/95 2,904,962 9/1959 Nicholson 60/102 1,854,288 4/1932 Bancel ct al. 165/70 X 3,376,9l7 4/1968 Fristoc ct al l65/lll X Primary Examiner-Kenneth W. Sprague Attorney, Agent, or Firm-Jennings Bailey, Jr.

[ 5 7] ABSTRACT A surface condensor for steam generated by nuclear power includes a plurality of cooling tubes arranged in a common casing having inlet openings for steam and an outlet opening above a plurality of basins for collecting condensate. Each basin is provided with a closeable return conduit for pure condensate containing a valve which is normally open. There is also a line through which polluted liquid can be drawn off from any basin provided with a normally closed valve. An arrangement for measuring the pollution in each basin opens the valve for polluted liquid in response to a leakage of coolant from the tubes and at the same time shuts off the flow to the leaking tube bundle.

The casing also supports a housing enclosing a plurality of turbines which are fed by the steam and which discharge to the condensor.

4 Claims, 4 Drawing Figures PAIENTED M18 6 74 "sum 1 OF IN ENIOR.

0N p E R w M m u PAIENTEDMIB 6 1 3.827.479

sum 2 or 2 INVENTOR. PETER F5353 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface condensor for steam generated by nuclear power, said condensor comprising a plurality of cooling tubes arranged in a common casing with an inlet opening for steam and a plurality of basins for collecting condensate and any cooling water leaking out from respective parts of the condensor, each basin being provided with a closable return conduit for pure condensate and a valve through which the basin can be connected to a drainage pipe for polluted liquid.

The requirement of purity of the feeding water to a steam-generating and condensing plant cannot be ignored without jeopardizing the operation of the equipment. Particularly strict requirements must be set for the feeding water in nuclear power plants having reactors of the direct cycle boiling type, since with these reactors the steam leaving to a turbine and the condensate returned from the turbine are radioactive. Not nearly such high requirements need be set for the purity of the cooling water to the turbine condensor.

2. The Prior Art From British Pat. No. 384,147 it is known to divide the condensation space of a surface condensor into several different compartments, each having a relatively narrow opening for condensate, each of these openings leading to a collecting chamber below which is provided with a two-way valve for connection to a drainage pipe for polluted water or to a return conduit for pure condensate. The known condensor comprises only one bundle of cooling tubes and each cooling tube passes through all the condensor compartments. If a coolant leakage should arise in one such compartment, therefore. there is no chance of closing off the flow of coolant in only the damaged condensor compartment. Instead condensation is avoided by opening the condensation space of the damaged compartment to the open air.

However, for steam generated in a nuclear reactor, such a solution would scarcely comply with the safety regulations concerning the risk of radioactive poisoning.

SUMMARY OF THE INVENTION This drawback is avoided with a condensor according to the invention which also has the advantage that repair work can be carried out without the technician having to come noticeably in contact with radioactive parts, and in such a short time that the time factor of the. radiation dose will be very low.

A surface condensor according to the invention is characterised in that the surface condensor comprises a plurality of cooling tubes bundles each provided with an inlet chamber and an outlet chamber for coolant and that said bundles are arranged in a plurality of groups being, each group arranged over a basin and having at least one valve means per group intended to close off the flow of cooling water through the group if there is a leakage of coolant.

The drainage is preferably arranged to be controlled primarily by the degree of impurity and secondarily by the water level in the basin and it is suitable for one basin to be arranged below each bundle of tubes in the condensor.

BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be further described with reference-to the accompanying drawings.

FIG. I. shows partly in section a perspective view of a steam turbine with generator and condensor.

FIG. 2 shows schematically the condensor of FIG. I sith coolant conduits, conduits for condensed water and the drainage system.

FIG. 3 a coolant tube bundle in vertical section and FIG. 4 shows the inlet and outlet for coolant to a bundle of tubes in vertical section on the line IV IV in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The turbine equipment shown in FIG. 1 consists of a turbine aggregate 1 and a condensor 2. The turbine aggregate 1 has a high pressure part 3 and a low pressure part 4, which operate on a common shaft 5 and drive a generator 6. Steam is led from a steam generator, not shown, which in this case is a nuclear reactor of direct cycle boiling type, into the high pressure part 3 where it drives two parallel-connected axial turbines 7. The steam is led from these turbine through a combined moisture separator and intermediate over-heater 8 to the low pressure part 4 where it drives eight parallelconnected axial turbines 9 arranged in pairs. The low pressure turbines 9 are enclosed in a common turbine housing 10 which is supported by the condensor 2 and at the same time serves as a steam inlet to the condensor. In this way the turbine housing 10 acquires almost as low a temperature as the condensor. The heat radiation losses are therefore small and the efficiency high.

The condensor 2 rests on five concrete bases 11 and has four parallel and horizontal coolant tube bundles 12 which are arranged one beside condensor casing 18. Brushings l6 and 17, provided condensor casing 13, bushing pins 16 and 17, respectively provided with lids l4 and 15, respectively, extend outward through the long sides of the casing 13 for closing the tube bundles 12 (FIG. 3).

As can be seen from FIG. 2, the four bundles 12 are located above and in the spaces between the five concrete bases 11. The bottom of the condensor casing 13 below each tube bundle 12 is in the form of an elongated channel-like basin 18. Outlet conduits 19 for condensed water lead from the basins l8 and may be provided with valves 43 which are normally open. The outlet conduits I9 meet in a collecting box or conduit 20 from which the condensed water is transported further by three parallel-connected pumps 21 to preheaters, not shown, for feed water. The cooling water flows to the tube bundles 12 through the main conduit 22 with branch conduits 23 and after passing through the tube bundles I2 is lead away through the outlet conduits 24 and collecting conduit 25 to a receptacles, not shown. Although the cooling water conduits 22 25 in FIG. 2 have been shown, for conservation of space in the drawing, above the tube bundles 12, they may be, and in fact generally are, located below the tube bundles as indicated in FIGS. 3 and 4. The inlet conduits 23 and outlet conduits 24 have valves 26 and 27, respectively, which are normally open. From the bottom of each basin 18 leads a drainage conduit 28 which is provided with a valve 29, normally closed. The drainage conduits 28 meet in a drainage collecting con- 3 duit 30 with a pump 31, which transports the drainage to a basin, not shown, in a waste handling system. lt can then usually be released to the surroundings immediately away, after a radioactivity test. A test unit 32 is fitted in each basin 18. If there is a leak to one of the basins 18, which can be ascertained in various suitable ways, for example by the test unit including members to measure the conductivity of the water in the basin, the test unit 32 shuts off the flow of coolant through the tube bundle 12 in question by shutting the coolant valves 26 and 27. The outlet valve 43 is also closed by the test unit 32. If, however, there is no such valve, the inlet to the condensation outlet 19 is arranged above the inlet to the drainage conduit 28 and immediately below the highest permitted water level, and may be in the form of an overflow. Furthermore, the test unit opens the drainage valve 29 and starts the drainage pump 31. When draining is completed the valve 29 is closed and the pump 31 stopped. The test unit may also include a level gauge which activates the drainage system if the basin should start to refill after the first draining process.

FIGS. 3 and 4 show a tube bundle 12 with connections for coolant. The bundle comprises a plurality of tubes 33 which are attached at the ends in tube plates 34 and 35, one of which (34) is radially enlarged in order to clamp one end of the bundle to the bunshing pin 17 projecting from the condensor casing. The other end of the tube bundle is freely movable in an axial direction, projects cut through the other bushing 16 and is provided with a head 36 which surrounds a relinking chamber 37 for the cooling water. Between the lid and the larger tube plate 34 is a water distributing chamber 38 having a vertical separating wall 39, an inlet nozzle 40 for connection to the branch conduit 23 for cooling water and an outlet nozzle 41 for connection to the outlet conduit 24. The coolant may consist of lake or sea water, which is normally not very clean.

If a coolant leakage should occur inside the condensor because of a tube rupture, the flow of coolant is shut off in the bundle in question and also the normal release of condensed water from the basin to the condensation pumps and the basin is connected to a drainage system. The condensation on the tubes will therefore cease and only a steadily decreasing leakage flow of coolant is carried to the basin. It is possible to omit the closing valves 26 and 27 in the cooling system, thus giving a cheaper construction but increased pumping costs since in such an embodiment the drainage pump 31 must operate continuously after a tube rupture. lf, upon a tube rupture, there is a risk that the basin will fill so far that it might overflow to an adjacent basin, this danger can be removed by means of intermediate walls 42 as shown in FIG. 2.

The invention is not limited to the embodiment shown and described. Many variations are feasible within the scope of the claims. For example the con densor may have a tubular casing which surrounds a tube aggregate which at least substantially fills out the cross-section of the condensor casing. At least some of the tube bundles lie above other tube bundles and the basins do not consist of the bottom of the condensor casing, but of channels or troughs located above the bottom and closed as the ends. The basins may then be located at different levels.

I claim:

1. Surface condensor arrangement for steam generated by nuclear power, said condensor comprising a casing having an inlet opening, a plurality of cooling tubes arranged in said casing, and a plurality of basins for collecting condensate from the casing with any cooling water leaking out from respective parts of the condensor, a drainage pipe for polluted liquid, each basin being provided with a closable return conduit for pure condensate and a valve through which the basin can be connected to said drainage pipe, in which the surface condensor comprises a plurality of cooling tube bundles each provided with an inlet chamber and an outlet chamber for coolant, said bundles being arranged in a plurality of groups, each group being arranged over a basin and having at least one valve means per group responsive to a leakage of coolant from the respective tube bundles to close off the flow of cooling water through the group.

2. Surface condensor according to claim 1, which includes draining means for the basin responsive to the degree of pollution in the basin.

3. Surface condensor according to claim 2, in which said draining means is further responsive to the water level in the basin.

4. Surface condensor according to claim 1, in which a basin is arranged below every bundle of tubes. 

